介電式電濕潤(EWOD)光偏折器之優化試驗研究

Abstract

隨著科技日新月異的發展，可調變光學偏折器在光學系統中，像是可3-D 調變的智慧照明系統、主動轉向頭燈、3-D 全像投影、激光雷達等，扮演舉足輕重的角色。為了改善傳統機械轉向系統具有體積大、靈敏度低及機械耗損等問題。過去已發展出許多非機械式的光偏折器。然而研發一個具有大角度、低電壓、高靈敏度、光束頻寬大、透光效率佳及光偏振獨立的單一電制光偏折元件，仍然是各方努力的目標。 目前電濕潤光偏折器已具備光束頻寬大、透光效率佳、光偏振獨立的特性。為了使電濕潤光偏折器具有低電壓與大偏折角度的特性，本文從電濕潤的基礎理論著手，分析交流電場作用與介電層、疏水層所使用的材料，對飽和接觸角的影響，並透過探討此系統所需使用的材料，包括具有高介電常數的P(VDF-TrFE)與PZT 作為介電層以及降低水溶液與絕緣油的界面張力，來減少電濕潤所需的外加電壓，並提升液體接觸角的變化量。此外，使用具有高折射率且與水溶液密度匹 配的絕緣油，來達成較大的光偏轉角。 最後，我們選用厚度600 nm 的P(VDF-TrFE)介電層，搭配30 nm 的AF1601疏水層，並在孔徑大小3 mm*3 mm 的腔體內灌入1wt%SDS 與CN:C12=67.62:32.38 的絕緣油，進行光偏折測試。結果顯示，此系統在外加100Hz 交流電壓11V時，可產生約+_30 o 的液面傾斜角，並造成約14 o ( +_7o )的光束偏折角。

As technology advances, variable optical deflector plays an important role in optical systems, such as 3-D lighting systems, adaptive front lighting system, 3-D holographic displays, Ladar, to name a few. With an attempt to overcome the bulk, high cost, slow speed, and lack of agility associate with mechanical beam steering approaches such as the dual-axis gimbaled mirror, several types of non mechanical optical deflections have been proposed over the years. Despites all these efforts, developing a wide-angle, low-voltage, high speed, polarization independent, high steering efficiency and broadband beam steering device is still a highly desirable goal. Electrowetting optical deflector (EOD) developed previously were known to have performance characteristics such as broadband, high steering efficiency, polarization independent. The main bottleneck to be overcome lies on lowering the operating voltage. To achieve low operating voltage and wide steering angle features, we started from the fundamental electrowetting theory to describe the limiting phenomena of contact angle saturation and analyzed the influence of the externally applied AC electric field, the dielectric layer material, and the hydrophobic layer, etc. in this dissertation. The dielectric layers with high K and low interfacial tension between the aqueous solution and insulating oils were investigated in order to investigate the possibility of reducing the operation voltage and the saturation of contact angle. Furthermore, we developed insulating oil with characteristics such as high refractive index and density identical to the adjacent aqueous solution to achieve wide-angle while lessening the influence of gravity. Finally, we utilized 600 nm-thick P(VDF-TrFE) and 30 nm-thick AF1601 to fabricate a deflector with an aperture size of 3 mm*3 mm. The deflection was filled with the aqueous (1wt%SDS) and the mixed oil (CN:C12=67.62: 32.38) to test the beam steering angle. We demonstrated our deflector to have switching performance of 30o tilt angle of flat meniscus interface, which led to 14 o ( +_7o )beam steering angle on two deflection axes.